BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Talks.cam//talks.cam.ac.uk// X-WR-CALNAME:Talks.cam BEGIN:VEVENT SUMMARY:3D Numerical Modelling of Compressible Coupled Magma/Mantle Dynami cs With Adaptive Mesh Refinement - Timo Heister ()\; Juliane Dannberg (Te xas A&\;M University ) DTSTART:20160610T080000Z DTEND:20160610T100000Z UID:TALK66423@talks.cam.ac.uk CONTACT:INI IT DESCRIPTION:Juliane Dannberg (dannberg@math.tamu.edu)\, Ryan Grove\, Timo Heister (heister@clemson.edu)

Melt generation and migration are imp ortant processes for the evolution of the Earth'\;s interior and impact the global convection of the mantle.
While they have b een the subject of numerous investigations\, the typical time and length-s cales of melt transport are vastly different from global mantle convection \, which determines where melt is generated. This makes it difficult to st udy mantle convection and melt migration in a unified framework. In additi on\, modelling magma dynamics poses the challenge of highly non-linear and spatially variable material properties\, in particular the viscosity.

Here\, we present our extension of the community mantle convection code ASPECT\, which adds the equations of two-phase flow of mel t and solid\, as an example for how these challenges can be addressed. Fir st\, We will analyse well-posedness\, existence\, and uniqueness of the p roblem. Then we will discuss the correct way to do a stable higher order finite element discretization. Finally\, the resulting linear system is s olved with an iterated solver preconditioned by a Schur complement-based block preconditioner. We demonstrate that applying adaptive mesh refinemen t to this type of problem is particularly advantageous\, as the resolution can be increased in mesh cells where melt is present and viscosity gradie nts are high\, whereas a lower resolution is sufficient in regions without melt. Together with a high-performance\, massively parallel implementatio n\, this allows for high resolution\, 3d\, compressible\, global mantle co nvection simulations coupled with melt migration.

We present benc hmarks of our solver to confirm the theoretical results\, and apply our so ftware to large-scale 3d simulations of melting and melt transport in mant le plumes interacting with the lithosphere to show robustness and parallel scalability of the linear solver. Our model incorporates the individual c ompressibilities of the solid and the fluid phase in addition to compactio n\, and we demonstrate that including these effects can change melt volume s by more than 20%. Moreover\, we show how including melting\, melt migrat ion and freezing of melt in global convection models can influence convect ion patterns and the distribution of chemical heterogeneities in the mantl e.

Our model of magma dynamics provides a framewo rk for modelling processes on different scales and investigating links bet ween processes occurring in the deep mantle and melt generation and migrat ion.






LOCATION:Seminar Room 1\, Newton Institute END:VEVENT END:VCALENDAR